Supermarket boss Richard Walker has revealed that pararmedics saved his life after he collapsed near the finish line of the London Marathon. The executive chairman of the Deeside-based Iceland supermarkets had been taking part with colleague Simon Felstead to raise money for Alzheimer's Research UK.

The run had been going well until two miles from the finish line when he collapsed and fell unconscious with hyperthermic shock. He wrote in an Instagram post that his body temperature was "42C and rising". He added: "Truth be told, I didn't train enough and pushed way too hard on the day."

The supermarket boss, who is in his 40s, had climbed to the top of Everest last year to raise money for charity and he added that he thought his collapse was down to "a little bit of Everest arrogance".

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It was his first marathon but he had climbed the world's highest mountain in May last year to raise more than £1m for The National Brain Appeal to build the world's first Rare Dementia Support Centre. After his collapse on Sunday, he thanked the St John Ambulance workers who he believes saved his life saying: "I came to about half an hour later surrounded by an amazing team of medics, covered in ice with all sorts of things stuck in me.

"I can't thank them enough - they were the true heroes of the day and I owe them my life. I'm so totally in awe of everyone who ran the marathon, and all the inspiring stories behind people's motivation for doing so. Seeing all the charity efforts was just so emotional."

St John Ambulance replied: "We hope you're recovering well Richard. Thank you so much for kind words for our hardworking volunteers!" Alzheimer's Research UK said: "This must have been so scary, Richard. We’re in awe of the huge effort you put into completing the London Marathon and relieved to hear you're on the mend. Wishing you a swift recovery and sending you our best wishes."

More than 50,000 people ran the 26.2-mile London Marathon on Sunday, including politicians, actors in character and amateurs in costume, helping to raise millions for charity. For the latest Welsh news delivered to your inbox sign up to our newsletter